Drill rigs are commonly used to drill for samples in connection with environmental testing of soil and ground water. Also, drill rigs are used during construction of various structures and in connection with land stability testing which is typically completed prior to any substantial construction on a site. Drill rigs are also used to drill wells for water.
Conventional drill rigs for such drilling operations generally comprise a drill spindle with means for attaching various drill tools, including, but not limited to, augers and drill rods. The drill spindle is mounted for rotation on a support frame. The support frame is typically mounted on a truck for transport to and from the drilling site. The spindle and the drill tools are driven by an internal combustion engine through a drive train. The drill rig also has means, usually a hydraulic cylinder, for raising and lowering the spindle and drill tools. Because such drilling operations require the drilling of and through many hard materials which can be located well below ground level, the auger or drill tool of such drill rigs is often large and requires a powerful internal combustion engine.
Such drill rigs can be dangerous in operation because there are many times when access to the area immediately surrounding the rotating drill tool is necessary for testing or for proper operation of the drill rig. For instance, access to the rotating drill tool is often needed for cleaning the drill tool, checking the soil condition, or removing cuttings which can accumulate around the hole being drilled.
Because of the size, speed, and risk involved in use of drill rigs, safety shutdown systems have been used in the past to stop drill spindle and drill tool rotation in an emergency. However, these prior shutdown systems require some type of physical actuation, such as pushing a "stop" button or hitting a wobble type switch. In other words, safety shutdown systems used with drill rigs in the past have been reactive, which requires operator action after the operator is already entangled in the drill tool, as opposed to proactive, which reduces the risk of entanglement of an operator in the first instance.
The prior art systems are able to shutdown a drilling rig in a number of different ways, such as shutting off of the engine which drives the drill spindle, placing the clutch of the drive train in the neutral position so that the drive train is disengaged from the engine, and/or applying a brake directly to the drive train to stop the drill spindle. U.S. Pat. No. 5,085,280, issued to Rassieur (the "'280 patent"), describes a safety shutdown system which employs all of the system shutdown ways discussed above, both separately and in various combinations. The apparatus of the '280 patent uses a wobble type switch adjacent to the drill spindle to activate the drill rig shutdown system. When the operator is in trouble, he or she can reach out and hit the wobble switch to stop the drill spindle. One safety feature of the '280 patent listed above is the brake which is applied directly to the drive train of the drill when the shutdown system is activated. The brake can decrease the time in which to stop spindle rotation. When the drill spindle is not engaged in drilling, several rotations may occur after the engine is shut off or the clutch disengaged. In that circumstance, the brake is useful in stopping the drill tool and spindle after an operator has become entangled in an attempt to reduce the degree of injury sustained. When the drill tool and spindle are engaged in drilling, the drill tool and spindle stop fairly quickly even without the brake. Use of the brake in that circumstance can reduce the stopping time by only a small amount. Although using a wobble switch provides the advantage of shutting down a drill rig by hitting the switch in any direction, access to the switch may be difficult if a drill rig operator is already entangled by the drill tool. Furthermore, by the time that a drill operator is able to hit a wobble switch, the operator may have already incurred substantial bodily injury.
From a safety standpoint, it is advantageous to have a pre-established safety zone which, if violated by the operator, would shut down the drill tool and spindle before the operator becomes entangled. On the other hand, it is also important that a safety shutdown system not impede the efficient operation of the drill rig. One system known in the art with a pre-established safety zone utilizes a large cage around parts of the drill tool and spindle to prevent the drill rig operator from gaining access to the drill tool and spindle during operation. However, the cage can hinder operation of the drill rig by not allowing the operator the easy access to the drill tool and spindle needed to perform some of the tasks listed above. Because use of the cage can hinder operation of the drill rig, many operators will not use it even if it is available to them.
Thus, there is a need in the art for a safety shutdown system for a drill rig which is proactive in operation (shuts down the drilling rig before the operator can become entangled) and which does not hinder the operation of the drill rig by not allowing the operator limited access to the drill rig during operation.